The effect of the PREMIER interventions on insulin sensitivity

Objective-This ancillary study of PREMIER sought to determine the effects on insulin sensitivity of a comprehensive behavioral intervention for hypertension with and without the Dietary Approaches to Stop Hypertension (DASH) dietary pattern. Research Design and Methods-Participants were assigned to one of three nonpharmacologic interventions for blood pressure (group A, advice only; group B, established; and group C, established plus DASH). The established intervention included weight loss, reduced sodium intake, increased physical activity, and moderate alcohol intake; the DASH dietary pattern was added to the established intervention for those in group C. The DASH dietary pattern is high in fruits, vegetables, and low-fat dairy products while being lower in total fat, saturated fat, and cholesterol. It is abundant in nutrients such as magnesium, calcium, and protein, which have been associated with improved insulin sensitivity. Insulin sensitivity was measured at baseline and at 6 months using the frequently sampled intravenous glucose tolerance test with minimal model analysis. Results-Both intervention groups decreased total calories, percentage of calories from fat, and sodium intake to similar levels, with similar amounts of energy expenditure and weight loss. Covariate differences seen only in group C included increased intake of protein, potassium, calcium, and magnesium. Compared with control subjects, insulin sensitivity improved significantly only in group C, from 1.96 to 2.95 (P=0.047). Group B did have a significant decrease in fasting insulin and glucose, but the changes in insulin sensitivity did not reach statistical significance when compared with control subjects. Conclusions-These results suggest that including the DASH dietary pattern as part of a comprehensive intervention for blood pressure control enhances insulin action beyond the effects of a comprehensive intervention that does not include DASH.